y2038: globally rename compat_time to old_time32

Christoph Hellwig suggested a slightly different path for handling
backwards compatibility with the 32-bit time_t based system calls:

Rather than simply reusing the compat_sys_* entry points on 32-bit
architectures unchanged, we get rid of those entry points and the
compat_time types by renaming them to something that makes more sense
on 32-bit architectures (which don't have a compat mode otherwise),
and then share the entry points under the new name with the 64-bit
architectures that use them for implementing the compatibility.

The following types and interfaces are renamed here, and moved
from linux/compat_time.h to linux/time32.h:

old				new
---				---
compat_time_t			old_time32_t
struct compat_timeval		struct old_timeval32
struct compat_timespec		struct old_timespec32
struct compat_itimerspec	struct old_itimerspec32
ns_to_compat_timeval()		ns_to_old_timeval32()
get_compat_itimerspec64()	get_old_itimerspec32()
put_compat_itimerspec64()	put_old_itimerspec32()
compat_get_timespec64()		get_old_timespec32()
compat_put_timespec64()		put_old_timespec32()

As we already have aliases in place, this patch addresses only the
instances that are relevant to the system call interface in particular,
not those that occur in device drivers and other modules. Those
will get handled separately, while providing the 64-bit version
of the respective interfaces.

I'm not renaming the timex, rusage and itimerval structures, as we are
still debating what the new interface will look like, and whether we
will need a replacement at all.

This also doesn't change the names of the syscall entry points, which can
be done more easily when we actually switch over the 32-bit architectures
to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 36 insertions, 12 deletions

diff --git a/include/linux/time32.h b/include/linux/time32.h
index 92c0ca092d93..0e0d7304d1a8 100644
--- a/include/linux/time32.h
+++ b/include/linux/time32.h
@@ -13,6 +13,31 @@
 
 #define TIME_T_MAX	(time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
 
+typedef s32		old_time32_t;
+
+struct old_timespec32 {
+	old_time32_t	tv_sec;
+	s32		tv_nsec;
+};
+
+struct old_timeval32 {
+	old_time32_t	tv_sec;
+	s32		tv_usec;
+};
+
+struct old_itimerspec32 {
+	struct old_timespec32 it_interval;
+	struct old_timespec32 it_value;
+};
+
+extern int get_old_timespec32(struct timespec64 *, const void __user *);
+extern int put_old_timespec32(const struct timespec64 *, void __user *);
+extern int get_old_itimerspec32(struct itimerspec64 *its,
+			const struct old_itimerspec32 __user *uits);
+extern int put_old_itimerspec32(const struct itimerspec64 *its,
+			struct old_itimerspec32 __user *uits);
+
+
 #if __BITS_PER_LONG == 64
 
 /* timespec64 is defined as timespec here */
@@ -183,18 +208,17 @@ extern struct timeval ns_to_timeval(const s64 nsec);
 extern struct __kernel_old_timeval ns_to_kernel_old_timeval(s64 nsec);
 
 /*
- * New aliases for compat time functions. These will be used to replace
- * the compat code so it can be shared between 32-bit and 64-bit builds
- * both of which provide compatibility with old 32-bit tasks.
+ * Old names for the 32-bit time_t interfaces, these will be removed
+ * when everything uses the new names.
  */
-#define old_time32_t		compat_time_t
-#define old_timeval32		compat_timeval
-#define old_timespec32		compat_timespec
-#define old_itimerspec32	compat_itimerspec
-#define ns_to_old_timeval32	ns_to_compat_timeval
-#define get_old_itimerspec32	get_compat_itimerspec64
-#define put_old_itimerspec32	put_compat_itimerspec64
-#define get_old_timespec32	compat_get_timespec64
-#define put_old_timespec32	compat_put_timespec64
+#define compat_time_t		old_time32_t
+#define compat_timeval		old_timeval32
+#define compat_timespec		old_timespec32
+#define compat_itimerspec	old_itimerspec32
+#define ns_to_compat_timeval	ns_to_old_timeval32
+#define get_compat_itimerspec64	get_old_itimerspec32
+#define put_compat_itimerspec64	put_old_itimerspec32
+#define compat_get_timespec64	get_old_timespec32
+#define compat_put_timespec64	put_old_timespec32
 
 #endif